Natural stain on teeth (human and lower animals) can be caused by a number of agents which are normally ingested such as coffee or tea. The stain forms on the pellicle film which forms on the teeth.
It has been surprisingly found by the present inventor that natural stain (contrasted with stain caused by antimicrobial agents) can be reduced by brushing with a paste containing a soluble pyrophosphate salt. While the prior art discloses compositions containing such salts, there is no suggestion that soluble pyrophosphates could reduce stain, natural or that caused by antimicrobials. As a matter of fact, U.S. Pat. No. 4,370,314, Jan. 25, 1983 to Gaffar indicates, in column 2 at lines 53-55, that soluble pyrophosphates would be ineffective against dental stain. This is supported by U.S. Pat. No. 3,927,201, Dec. 16, 1975 to Baines et al. wherein it is indicated that if sodium pyrophosphate decahydrate is used as an abrasive, the amount of the salt solubilized should be restricted to less than about 30% to enable the cleaning/abrasivity to be retained.
It is an object of the present invention to provide effective methods for reducing natural stain.
It is a further object of the present invention to provide methods which employ toothpastes containing soluble pyrophosphate salts as the stain reducing agent.
These and other objects will become more apparent from the detailed description which follows.
All percentages and ratios used herein are by weight unless otherwise specified.